java解析xml格式的字符串（详解Java解析XML的四种方法）

XML现在已经成为一种通用的数据交换格式,它的平台无关性,语言无关性,系统无关性,给数据集成与交互带来了极大的方便
  
  
  
  
  
  
  
  
。对于XML本身的语法知识与技术细节,需要阅读相关的技术文献,这里面包括的内容有DOM(Document Object Model),DTD(Document Type Definition),SAX(Simple API for XML),XSD(Xml Schema Definition),XSLT(Extensible Stylesheet Language Transformations),具体可参阅w3c官方网站文档http://www.w3.org获取更多信息 
  
  
  
  
  
  
  
 。

XML在不同的语言里解析方式都是一样的,只不过实现的语法不同而已 


 


 


 


 


 


 


 


 。基本的解析方式有两种,一种叫SAX
  
  
  
  
  
  
  
  
，另一种叫DOM
 
 
 
 
 
 
 
 
。SAX是基于事件流的解析,DOM是基于XML文档树结构的解析  
   
   
   
   
   
   
   
 。假设我们XML的内容和结构如下:

ddviplinux 

m 

30 

本文使用JAVA语言来实现DOM与SAX的XML文档生成与解析 

 

 

 

 

 

 

 

 。 

首先定义一个操作XML文档的接口XmlDocument 它定义了XML文档的建立与解析的接口

 

 

 

 

 

 

 

 
。

package com.alisoft.facepay.framework.bean;  /**  *  * @author hongliang.dinghl  * 定义XML文档建立与解析的接口  */  public interface XmlDocument {  /**  * 建立XML文档  * @param fileName 文件全路径名称  */  public void createXml(String fileName);  /**  * 解析XML文档  * @param fileName 文件全路径名称  */  public void parserXml(String fileName);  } 

1.DOM生成和解析XML文档

为 XML 文档的已解析版本定义了一组接口                。解析器读入整个文档 
  
  
  
  
  
  
  
 ，然后构建一个驻留内存的树结构 


 


 


 


 


 


 


 


 ，然后代码就可以使用 DOM 接口来操作这个树结构 
 

 
 

 
 

 
 

 
 

 
 

 
 

 
 

 。优点：整个文档树在内存中
 
 
 
 
 
 
 
 
，便于操作；支持删除                、修改  
 
  
 
  
 
  
 
  
 
  
 
  
 
  
 
 、重新排列等多种功能；缺点：将整个文档调入内存（包括无用的节点）  
   
   
   
   
   
   
   
 ，浪费时间和空间；使用场合：一旦解析了文档还需多次访问这些数据；硬件资源充足（内存
















、CPU）
















。 

package com.alisoft.facepay.framework.bean;  import java.io.FileInputStream;  import java.io.FileNotFoundException;  import java.io.FileOutputStream;  import java.io.IOException;  import java.io.InputStream;  import java.io.PrintWriter;  import javax.xml.parsers.DocumentBuilder;  import javax.xml.parsers.DocumentBuilderFactory;  import javax.xml.parsers.ParserConfigurationException;  import javax.xml.transform.OutputKeys;  import javax.xml.transform.Transformer;  import javax.xml.transform.TransformerConfigurationException;  import javax.xml.transform.TransformerException;  import javax.xml.transform.TransformerFactory;  import javax.xml.transform.dom.DOMSource;  import javax.xml.transform.stream.StreamResult;  import org.w3c.dom.Document;  import org.w3c.dom.Element;  import org.w3c.dom.Node;  import org.w3c.dom.NodeList;  import org.xml.sax.SAXException;  /**  *  * @author hongliang.dinghl  * DOM生成与解析XML文档  */  public class DomDemo implements XmlDocument {  private Document document;  private String fileName;  public void init() {  try {  DocumentBuilderFactory factory = DocumentBuilderFactory  .newInstance();  DocumentBuilder builder = factory.newDocumentBuilder();  this.document = builder.newDocument();  } catch (ParserConfigurationException e) {  System.out.println(e.getMessage());  }  }  public void createXml(String fileName) {  Element root = this.document.createElement("employees");  this.document.appendChild(root);  Element employee = this.document.createElement("employee");  Element name = this.document.createElement("name");  name.appendChild(this.document.createTextNode("丁宏亮"));  employee.appendChild(name);  Element sex = this.document.createElement("sex");  sex.appendChild(this.document.createTextNode("m"));  employee.appendChild(sex);  Element age = this.document.createElement("age");  age.appendChild(this.document.createTextNode("30"));  employee.appendChild(age);  root.appendChild(employee);  TransformerFactory tf = TransformerFactory.newInstance();  try {  Transformer transformer = tf.newTransformer();  DOMSource source = new DOMSource(document);  transformer.setOutputProperty(OutputKeys.ENCODING, "gb2312");  transformer.setOutputProperty(OutputKeys.INDENT, "yes");  PrintWriter pw = new PrintWriter(new FileOutputStream(fileName));  StreamResult result = new StreamResult(pw);  transformer.transform(source, result);  System.out.println("生成XML文件成功!");  } catch (TransformerConfigurationException e) {  System.out.println(e.getMessage());  } catch (IllegalArgumentException e) {  System.out.println(e.getMessage());  } catch (FileNotFoundException e) {  System.out.println(e.getMessage());  } catch (TransformerException e) {  System.out.println(e.getMessage());  }  }  public void parserXml(String fileName) {  try {  DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();  DocumentBuilder db = dbf.newDocumentBuilder();  Document document = db.parse(fileName);  NodeList employees = document.getChildNodes();  for (int i = 0; i < employees.getLength(); i++) {  Node employee = employees.item(i);  NodeList employeeInfo = employee.getChildNodes();  for (int j = 0; j < employeeInfo.getLength(); j++) {  Node node = employeeInfo.item(j);  NodeList employeeMeta = node.getChildNodes();  for (int k = 0; k < employeeMeta.getLength(); k++) {  System.out.println(employeeMeta.item(k).getNodeName()  + ":" + employeeMeta.item(k).getTextContent());  }  }  }  System.out.println("解析完毕");  } catch (FileNotFoundException e) {  System.out.println(e.getMessage());  } catch (ParserConfigurationException e) {  System.out.println(e.getMessage());  } catch (SAXException e) {  System.out.println(e.getMessage());  } catch (IOException e) {  System.out.println(e.getMessage());  }  }  } 

2.SAX生成和解析XML文档

为解决DOM的问题 

 

 

 

 

 

 

 

 ，出现了SAX                        。SAX 

 

 

 

 

 

 

 

 
，事件驱动 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 。当解析器发现元素开始
  
  
  
  
  
  
  
  、元素结束  
  
  
  
  
  
  
  
 、文本
 


 


 


 


 


 


 


 


、文档的开始或结束等时                ，发送事件 
 

 
 

 
 

 
 

 
 

 
 

 
 

 
 

 ，程序员编写响应这些事件的代码
















，保存数据
























。优点：不用事先调入整个文档                        ，占用资源少；SAX解析器代码比DOM解析器代码小 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 ，适于Applet
























，下载                。缺点：不是持久的；事件过后                ，若没保存数据 
 
  
 
  
 
  
 
  
 
  
 
  
 
  
 
  ，那么数据就丢了；无状态性；从事件中只能得到文本















，但不知该文本属于哪个元素；使用场合：Applet;只需XML文档的少量内容
  
  
  
  
  
  
  
  
，很少回头访问；机器内存少；

Java代码：

package com.alisoft.facepay.framework.bean; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import javax.xml.parsers.ParserConfigurationException; import javax.xml.parsers.SAXParser; import javax.xml.parsers.SAXParserFactory; import org.xml.sax.Attributes; import org.xml.sax.SAXException; import org.xml.sax.helpers.DefaultHandler; /** * * @author hongliang.dinghl * SAX文档解析 */ public class SaxDemo implements XmlDocument { public void createXml(String fileName) { System.out.println(">"); } public void parserXml(String fileName) { SAXParserFactory saxfac = SAXParserFactory.newInstance(); try { SAXParser saxparser = saxfac.newSAXParser(); InputStream is = new FileInputStream(fileName); saxparser.parse(is, new MySAXHandler()); } catch (ParserConfigurationException e) { e.printStackTrace(); } catch (SAXException e) { e.printStackTrace(); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } } class MySAXHandler extends DefaultHandler { boolean hasAttribute = false; Attributes attributes = null; public void startDocument() throws SAXException { System.out.println("文档开始打印了"); } public void endDocument() throws SAXException { System.out.println("文档打印结束了"); } public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException { if (qName.equals("employees")) { return; } if (qName.equals("employee")) { System.out.println(qName); } if (attributes.getLength() > 0) { this.attributes = attributes; this.hasAttribute = true; } } public void endElement(String uri, String localName, String qName) throws SAXException { if (hasAttribute && (attributes != null)) { for (int i = 0; i < attributes.getLength(); i++) { System.out.println(attributes.getQName(0) + attributes.getValue(0)); } } } public void characters(char[] ch, int start, int length) throws SAXException { System.out.println(new String(ch, start, length)); } } package com.alisoft.facepay.framework.bean;  import java.io.FileInputStream;  import java.io.FileNotFoundException;  import java.io.IOException;  import java.io.InputStream;  import javax.xml.parsers.ParserConfigurationException;  import javax.xml.parsers.SAXParser;  import javax.xml.parsers.SAXParserFactory;  import org.xml.sax.Attributes;  import org.xml.sax.SAXException;  import org.xml.sax.helpers.DefaultHandler;  /**  *  * @author hongliang.dinghl  * SAX文档解析  */  public class SaxDemo implements XmlDocument {  public void createXml(String fileName) {  System.out.println(">");  }  public void parserXml(String fileName) {  SAXParserFactory saxfac = SAXParserFactory.newInstance();  try {  SAXParser saxparser = saxfac.newSAXParser();  InputStream is = new FileInputStream(fileName);  saxparser.parse(is, new MySAXHandler());  } catch (ParserConfigurationException e) {  e.printStackTrace();  } catch (SAXException e) {  e.printStackTrace();  } catch (FileNotFoundException e) {  e.printStackTrace();  } catch (IOException e) {  e.printStackTrace();  }  }  }  class MySAXHandler extends DefaultHandler {  boolean hasAttribute = false;  Attributes attributes = null;  public void startDocument() throws SAXException {  System.out.println("文档开始打印了");  }  public void endDocument() throws SAXException {  System.out.println("文档打印结束了");  }  public void startElement(String uri, String localName, String qName,  Attributes attributes) throws SAXException {  if (qName.equals("employees")) {  return;  }  if (qName.equals("employee")) {  System.out.println(qName);  }  if (attributes.getLength() > 0) {  this.attributes = attributes;  this.hasAttribute = true;  }  }  public void endElement(String uri, String localName, String qName)  throws SAXException {  if (hasAttribute && (attributes != null)) {  for (int i = 0; i < attributes.getLength(); i++) {  System.out.println(attributes.getQName(0)  + attributes.getValue(0));  }  }  }  public void characters(char[] ch, int start, int length)  throws SAXException {  System.out.println(new String(ch, start, length));  }  } 

3.DOM4J生成和解析XML文档

DOM4J 是一个非常非常优秀的Java XML API 
  
  
  
  
  
  
  
 ，具有性能优异
 
 
 
 
 
 
 
 、功能强大和极端易用使用的特点 


 


 


 


 


 


 


 


 ，同时它也是一个开放源代码的软件 
 
  
 
  
 
  
 
  
 
  
 
  
 
  
 
  。如今你可以看到越来越多的 Java 软件都在使用 DOM4J 来读写 XML
 
 
 
 
 
 
 
 
，特别值得一提的是连 Sun 的 JAXM 也在用 DOM4J















。

Java代码：

package com.alisoft.facepay.framework.bean; import java.io.File; import java.io.FileWriter; import java.io.IOException; import java.io.Writer; import java.util.Iterator; import org.dom4j.Document; import org.dom4j.DocumentException; import org.dom4j.DocumentHelper; import org.dom4j.Element; import org.dom4j.io.SAXReader; import org.dom4j.io.XMLWriter; /** * * @author hongliang.dinghl * Dom4j 生成XML文档与解析XML文档 */ public class Dom4jDemo implements XmlDocument { public void createXml(String fileName) { Document document = DocumentHelper.createDocument(); Element employees=document.addElement("employees"); Element employee=employees.addElement("employee"); Element name= employee.addElement("name"); name.setText("ddvip"); Element sex=employee.addElement("sex"); sex.setText("m"); Element age=employee.addElement("age"); age.setText("29"); try { Writer fileWriter=new FileWriter(fileName); XMLWriter xmlWriter=new XMLWriter(fileWriter); xmlWriter.write(document); xmlWriter.close(); } catch (IOException e) { System.out.println(e.getMessage()); } } public void parserXml(String fileName) { File inputXml=new File(fileName); SAXReader saxReader = new SAXReader(); try { Document document = saxReader.read(inputXml); Element employees=document.getRootElement(); for(Iterator i = employees.elementIterator(); i.hasNext();){ Element employee = (Element) i.next(); for(Iterator j = employee.elementIterator(); j.hasNext();){ Element node=(Element) j.next(); System.out.println(node.getName()+":"+node.getText()); } } } catch (DocumentException e) { System.out.println(e.getMessage()); } System.out.println("dom4j parserXml"); } }

4.JDOM生成和解析XML  

为减少DOM   
   
   
   
   
   
   
   
 、SAX的编码量  
   
   
   
   
   
   
   
 ，出现了JDOM；优点：20-80原则 

 

 

 

 

 

 

 

 ，极大减少了代码量
  
  
  
  
  
  
  
  
。使用场合：要实现的功能简单

 

 

 

 

 

 

 

 
，如解析
 

 

 

 

 

 

 

 

、创建等                ，但在底层 
 

 
 

 
 

 
 

 
 

 
 

 
 

 
 

 ，JDOM还是使用SAX（最常用）

 

 

 

 

 

 

 

 、DOM                 、Xanan文档 
  
  
  
  
  
  
  
 。

package com.alisoft.facepay.framework.bean; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import java.util.List; import org.jdom.Document; import org.jdom.Element; import org.jdom.JDOMException; import org.jdom.input.SAXBuilder; import org.jdom.output.XMLOutputter; /** * * @author hongliang.dinghl * JDOM 生成与解析XML文档 * */ public class JDomDemo implements XmlDocument { public void createXml(String fileName) { Document document; Element root; root=new Element("employees"); document=new Document(root); Element employee=new Element("employee"); root.addContent(employee); Element name=new Element("name"); name.setText("ddvip"); employee.addContent(name); Element sex=new Element("sex"); sex.setText("m"); employee.addContent(sex); Element age=new Element("age"); age.setText("23"); employee.addContent(age); XMLOutputter XMLOut = new XMLOutputter(); try { XMLOut.output(document, new FileOutputStream(fileName)); } catch (FileNotFoundException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } public void parserXml(String fileName) { SAXBuilder builder=new SAXBuilder(false); try { Document document=builder.build(fileName); Element employees=document.getRootElement(); List employeeList=employees.getChildren("employee"); for(int i=0;iElement employee=(Element)employeeList.get(i); List employeeInfo=employee.getChildren(); for(int j=0;jSystem.out.println(((Element)employeeInfo.get(j)).getName()+":"+((Element)employeeInfo.get(j)).getValue()); } } } catch (JDOMException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } }